Unless otherwise indicated herein, the description provided in this section is not prior art to the claims and is not admitted to be prior art by inclusion in this section.
A cellular wireless network may include a number of base stations that radiate to define wireless coverage areas, such as cells and cell sectors, in which user equipment devices (UEs) such as cell phones, tablet computers, tracking devices, embedded wireless modules, and other wirelessly equipped communication devices, can operate. In turn, each base station may be coupled with network infrastructure that provides connectivity with one or more transport networks. With this arrangement, a UE within coverage of the network may engage in air interface communication with a base station and may thereby communicate via the base station with various remote network entities or with other UEs.
For instance, in a network operating according to a Long Term Evolution (LTE) protocol, base stations may be coupled to network infrastructure that provides connectivity with one or more packet-data networks, such as the Internet, as well as one or more service platforms, such as an Internet Multimedia Subsystem (IMS) platform that provides access to particular types of packet-based services (e.g., voice over Internet Protocol (VoIP), streaming video, interactive gaming, etc.). This network infrastructure may include a controller such as a mobility management entity (MME), a gateway system such as a serving gateway (SGW) coupled to one or more packet-data network gateways (PGWs), a subscriber profile database such as a home subscriber system (HSS), and a policy server such as a policy charging and rules function (PCRF), among other entities. It should be understood that a cellular wireless network's infrastructure may also provide connectivity to various other transport networks and/or take various other forms as well.
When a UE first enters into the coverage of a cellular wireless network, the UE may engage in a process of registering or “attaching” with the network, which may trigger setup of various communication channels for the UE and/or reservation of various communication resources for the UE. For instance, upon first detecting coverage of a base station, the UE may transmit an attach request message to the base station, which the base station may forward to a network controller such as an MME. Upon authenticating and authorizing the UE, the network controller may then engage in further signaling with the base station and with an SGW, which may in turn engage in signaling with a PGW, ultimately resulting in setup of one or more bearer connections or “bearers” each extending, via the base station, between the UE and the PGW, through which the UE can then engage in packet-data communication via the PGW.
Each bearer established for a UE may define a logical communication tunnel that includes a radio bearer portion extending between the UE and the base station, and an access bearer portion extending between the base station and the PGW via the SGW. Further, each bearer may have a designated quality-of-service (QoS) level, which may dictate how the packet data transmission along the bearer is handled by the network. For instance, a bearer could have a relatively high QoS level, according to which network nodes (such as the base station, SGW, and various routers) along the bearer path could be set to prioritize routing of data on the bearer over routing of data on other bearers, perhaps to guarantee a particular minimum bit rate, a particular maximum level of packet delay, and/or a particular maximum level of packet loss. Alternatively, a bearer could have a relatively low QoS level, such as a “best efforts” QoS level, according to which nodes along the bearer path would simply do their best to route data of the bearer, subject to higher priority handling of other bearer traffic.
In practice, a network such as this may initially establish for a UE one or more default bearers to enable the UE to engage in certain basic communications, with each default bearer having a respective QoS level. By way of example, the network may initially establish for the UE a default Internet bearer with a best-efforts QoS level, for use by the UE to engage in general Internet communications such as web browsing, e-mail messaging, and the like. Further, if the UE subscribes to any IMS-based services such as VoIP call service, the network may initially establish for the UE a default IMS signaling bearer with a medium QoS level, for use by the UE to engage in session setup signaling (such as Session Initiation Protocol (SIP) signaling) with the IMS platform to facilitate setup of such IMS-based services.
As the UE is served by the network, the network may then establish additional bearers for the UE as needed. For example, if the UE has an IMS signaling bearer, the UE may engage in signaling over that bearer with an IMS platform to request setup of an IMS-based communication session, which typically requires a new dedicated bearer between the UE and the IMS platform. In response to this signaling, the network may then attempt to establish a new dedicated IMS bearer with a QoS level that corresponds to the type of IMS-based session being requested, such as a bearer having a high QoS level for a VoIP call. This may involve signaling from the IMS platform to the PCRF, from the PCRF to the PGW, from the PGW to the SGW, from the SGW to the MME, from the MME to the base station, and from the base station to the UE. Once the dedicated IMS bearer is established, the UE may then send and receive media content of the session over that dedicated IMS bearer.